System and Method For Situational Awareness

ABSTRACT

A non-transitory computer readable medium containing computer program instructions for monitoring whether persons in a group are each away from an associated vehicle. In one embodiment, the computer system receives an association between each of multiple persons in the group with one of multiple vehicles and automatically receives digital information, derived from measured rf signal strength, indicating whether any one of multiple persons in the group has moved from a first relatively close position with respect to an associated vehicle and farther away from the associated vehicle than the first position. A notification is sent from the computer system to at least one device associated with a person in the group based on received information that a first of said multiple persons is farther away from the associated vehicle than the first relatively close position is from the associated vehicle.

RELATED APPLICATIONS

This application is related to each of the following applications filedon the same date as this application and assigned to the assignee ofthis invention: U.S. application Ser. No. ______ (Attorney Docket Number12066-005); U.S. application Ser. No. ______ (Attorney Docket Number12066-006); and U.S. application Ser. No. ______ (Attorney Docket Number12066-007).

FIELD OF THE INVENTION

The present invention relates to security, safety and situationalawareness. In one application the invention enables monitoring andcoordination of law enforcement or security personnel based on relativelocation and availability of personnel.

BACKGROUND

Personnel working in the fields of law enforcement, military operationsand security are often engaged in patrolling. While performing routineduties such as monitoring assigned areas, the personnel may travel overa relatively large geographic area with, for example, a motorizedvehicle, a bicycle or a horse. The personnel may stop on an impromptubasis, and then exit the vehicle or dismount. Although the personneltypically have a communications link with the central facility, the factthat personnel have made a stop or left a vehicle (e.g., a patrol car)and become engaged in an activity, may not be immediately communicatedto the central facility. Greater knowledge of personnel activities canimprove, among other things, coordination of operations in anorganization.

SUMMARY OF THE INVENTION

The invention is useful in contexts where it is desirable to determinethe status, e.g., availability, of an individual during conduct of workactivities. Status information is particularly useful to law enforcementand security operations. Awareness of a relative position, by itself,can provide sufficient information about an individual to generatestatus information. The same status information can be used to create analert with respect to a potential danger or to remove an existing alert.A feature of the invention is recognition that real time knowledge ofwhen an officer exits or re-enters a patrol car or other type of vehicle(generally referred to as a vehicle) can be had without relying solelyon voice communications. The resulting improvement in situationalawareness enhances operational efficiencies and coordination ofactivities. By receiving alerts as to when an officer leaves a vehicle,a central facility or command center can automatically monitor personnelwho are not currently in communication with the command center, becomeaware that the officer is engaged in an away-from-vehicle activity, andpromptly address risks of danger. In one example, an alert indicatingthat an officer is located external to a patrol car, or has moved morethan a minimum distance away from a vehicle, allows a command centerofficer to determine that a particular officer is not immediatelyavailable to respond to another call or incident. It also enables thecommand center to issue an alert when the officer has been away from thevehicle for longer than a predetermined period of time, thereby raisingconcern for the safety of personnel.

In one series of embodiments, a non-transitory computer readable mediumcontains program instructions representing software executable in acentral monitoring system comprising a computer system including amicroprocessor memory media and storage media and connected to anetwork. The instructions, when executed by the computer system, causethe computer system to perform method steps for monitoring the status ofmultiple persons in a group based on distance between a communicationsdevice associated with each person and one of multiple vehicles, eachperson in the group being associated with one of the vehicles, thestatus being indicative as to whether each person in the group has movedaway from an associated vehicle or returned thereto. Each communicationsdevice is a first device in a pair of first and second devices, and thefirst devices are carried by persons in the group while the seconddevices are each positioned at one of the associated vehicles. Themethod implemented by the program instruction includes receiving, by acentral monitoring system comprising a processor, digital data from atleast one member in each pair of devices in communication across anetwork with the processor of the central monitoring system, andprocessing the digital data received from the at least one member ineach pair of devices, by (i) identifying each communications device ineach pair of devices, (ii) associating the communications device in eachpair of devices with a person in the group who is assigned to thecommunications device, and (iii) assimilating location statusinformation from the data received from at least one member in each pairof devices. The data is based on a distance between the devices in eachpair derived from strength of a RF signal transmitted from one device inthe pair toward the other device in the pair. The location statusinformation is indicative of persons in the group being in a firststatus when the person associated with the communications device in thepair has moved beyond a predetermined range of distance from thevehicle. Location status information is provided to a display screen toprovide notification when a person in the group is in the first status.In one embodiment, the step of receiving digital data, includingassimilating the data, is performed periodically to automatically placestatus information in a database and periodically update the database toprovide new status information regarding movement of each person in thegroup with respect to an associated vehicle. Also in an embodiment ofthe invention, the outputting of updated location status information toa display screen is performed periodically to provide updatednotification of when a person in the group is in the first status.

In another series of embodiments, a non-transitory computer readablemedium contains program instructions representing software executable ina central monitoring system comprising a computer system including amicroprocessor memory media and storage media and connected to anetwork. When executed by the computer system, the instructions causethe computer system to perform method steps for monitoring whether oneor more persons in a group have each been away from an associatedvehicle for longer than a predetermined time period. The methodaccording to the program instructions includes (i) receiving into thecomputer system an association between each of multiple persons in thegroup with a vehicle and (ii) automatically receiving into the computersystem digital information, derived from measured rf signal strength andsent via the network, indicating whether any one of multiple persons inthe group has moved from a first relatively close position with respectto an associated vehicle and farther away from the associated vehiclethan the first position. A timer function is initiated in the computersystem if the information the computer system receives indicates that afirst of said multiple persons in the group has moved farther away fromthe associated vehicle than the first position.

Updated information is periodically received into the computer system.The updated information is derived from measured rf signal strength andindicates whether the first of said multiple persons remains fartheraway from the associated vehicle than the first relatively closeposition or has moved to a position at least as close to the associatedvehicle as the first relatively close position. A notification is sentfrom the computer system to at least one device associated with a secondperson in the group if, after a predefined time period determined withthe timer function, it is determined based on received updatedinformation that the first of said multiple persons remains farther awayfrom the associated vehicle than the first relatively close position.The notification indicates that the first of said multiple persons hasremained farther away from the associated vehicle than the firstrelatively close position during the entire predefined time period.

In another series of embodiments, a non-transitory computer readablemedium contains program instructions representing software executable ina central monitoring system comprising a computer system including amicroprocessor memory media and storage media and connected to anetwork. When executed by the computer system, the instructions causethe computer system to perform method steps for monitoring whetherpersons in a group are each away from an associated vehicle. The methodimplemented by the program instructions includes receiving into thecomputer system an association between each of multiple persons in thegroup with one of multiple vehicles and automatically receiving into thecomputer system digital information, indicating whether any one ofmultiple persons in the group has moved from a first relatively closeposition with respect to an associated vehicle and farther away from theassociated vehicle than the first position. The digital information isderived from measured rf signal strength. A notification is sent fromthe computer system to at least one device associated with a person inthe group. The notification is based on received information that afirst of said multiple persons is farther away from the associatedvehicle than the first relatively close position is from the associatedvehicle.

In another series of embodiments, a non-transitory computer readablemedium contains program instructions representing software executable ina central monitoring system comprising a computer system including amicroprocessor memory media and storage media and connected to anetwork. The instructions, when executed by the computer system, causethe computer system to perform method steps for providing persons in agroup status information and information about the whereabouts of otherpersons in the group, including whether persons in the group have movedaway from an associated vehicle or returned to the vehicle. The methodimplemented by the program instructions includes periodically receivinginto a computer system information derived from measured rf signalstrength and automatically sent in digital form via a cellular networkfrom one or more portable devices. The received information indicateswhether any of the persons has moved from a first relatively closeposition with respect to an associated vehicle to beyond the firstposition and farther away from the associated vehicle than the firstposition. Also according to the method, location information is receivedinto the computer system, from the portable devices. The locationinformation is sent via the network for multiple ones of the persons.The location information may be based on vehicle position or position ofa person when the person is in the first relatively close position withrespect to the associated vehicle. Status information is sent from thecomputer system to each of the portable devices via the cellularnetwork, for graphically indicating the location of each person on a mapand indicating on the map whether each person is (i) at a firstrelatively close position with respect to an associated vehicle or (ii)beyond the first position and farther away from the associated vehiclethan the first position. In one embodiment the location information isperiodically sent via the network for multiple ones of the persons. Thelocation information may be based on vehicle position. According to anembodiment the status information is periodically sent to provideupdates of the status information to each of the portable devices tographically update the location of each person on a map and indicate onthe map whether each person is beyond the first position and fartheraway from the associated vehicle than the first position.

In another series of embodiments, a non-transitory computer readablemedium contains program instructions representing software executable ona computer system of the type having a microprocessor, a memory mediumand a storage medium. The instructions, when executed by the computersystem, cause the computer system to perform method steps forautomatically monitoring or notifying when one or more persons in agroup move away from an associated vehicle or return toward the vehicle.The method steps include storing and providing access to modify adatabase in the computer system which identifies a plurality of portablecommunications devices, each device configured to exchange data with thecomputer system. The database associates each portable device with aperson in the group assigned to have the device in his or herpossession. Further, the position information is received into the database. The position information is derived from a rf signal strengthwhenever sent from each portable communications device via the network,and indicates whether the person, having possession of the portabledevice, has moved a distance away from the associated vehicle. Theinformation received includes data indicating whether each person havingpossession of one of the portable communications devices is (i) in afirst position relatively close to or within the associated vehicle or(ii) has moved away from the associated vehicle to a second position or(iii) has moved from the second position to the first relatively closeposition. Updated status information is automatically sent from thecomputer system to at least one device connected to receive data via thenetwork. The updated status information identifies each person inpossession of a portable communications device who (i) has moved awayfrom a first position relatively close to or within the associatedvehicle to a second position; or (ii) has moved from the second positionto the relatively close first position.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout, and wherein:

FIG. 1A illustrates a system for improving situational awareness in alaw enforcement operation based on provision of a RF link between aportable client device and a stationary device;

FIG. 1B illustrates the system of FIG. 1A under a condition in which theRF link between the portable device and the stationary device is broken;

FIGS. 1C and 1D illustrate issuance of alerts by a server under thebroken link condition of FIG. 1B;

FIGS. 2A-2C illustrate a log-in sequence, a monitoring routine and alog-off sequence in a method according to the invention;

FIGS. 3A-3E are simplified flow charts illustrating subroutine functionsperformed on the portable client device;

FIGS. 4A and 4B are simplified flow charts illustrating subroutinefunctions performed on a server in the system shown in FIGS. 1; and

FIGS. 5A-5I illustrate an exemplary sequence of views on the display ofa hand-held device, such as a mobile telephone according to anembodiment of the invention.

In accord with common practice, the various described features are notdrawn to scale, but are drawn to emphasize specific features relevant tothe invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1A illustrates a system for improving situational awareness in alaw enforcement operation based on provision of a breakable wirelessradio frequency (RF) link 8 between two devices and a wireless dataconnection 9 a or 9 b between each device and a server. Both of thedevices may be portable devices. Further, both of the devices may behandheld devices. At least one device serves as a transmitter or beaconwhich sends a signal to the other device which serves as a receiver.

Various types of wireless signals can be used to form RF links tomonitor signal strength as an indication of distance between twodevices. Embodiments of the invention are directed to monitoring whethersome minimum level of separation exists between the devices based on ameasure of signal strength. Precision in determining an actual distanceof separation is less critical than providing a high level of confidenceand reliability that at least a minimum distance of separation exists.Features of the invention are based on recognition that situationalawareness can be improved by determining whether some minimum separationdistance exists between two RF devices using an operational frequencyand wireless protocol common to the two devices. Such a minimumseparation distance need not be determined with great precision. Nor isit necessary to determine the separation distance. Rather, it isrecognized that short range wireless signals, e.g., in accord with aBluetooth technology specification, are useful to provide a level ofsituational awareness based on some minimum distance of separationbetween an officer carrying one of the two devices and the other one ofthe devices.

Under a first condition, referred to as Condition One, the RF link 8between the two devices is considered established and detected when thereceiving device receives a predefined minimum power level. When thelink 8 is of sufficient strength to be detected it is referred to as abreakable link. Under a second condition, referred to as Condition Two,when a previously established link no longer exhibits the minimum powerlevel the link 8 is classified as no longer detected. When there is atransition from the Condition One to the Condition Two, the status ofthe link 8 is referred to as broken. An application in at least one ofthe devices applies criteria to determine whether a breakable link isbroken.

A network 10, associated with a law enforcement operation 6, e.g., acity police department, includes a server 12 linked to cellular system14. The server is a computer system comprising a processor, memory andstorage media. As further described herein, the server houses a databasewhich is written to the storage media loaded into memory andperiodically and updated. The system 14, which includes base stations,towers and other typical equipment, is indicated by a tower in theFigures. The cellular system 14 transmits cellular wireless signals tonumerous portable devices, including both mobile and stationary devices.The mobile device is a mobile client device. The exemplary mobile clientdevice is a mobile telephone 18 which has a conventional cellularwireless two-way communication link 9 a with the cellular system 14. Theexemplary stationary device is a portable computer (PC) 20 which also isin two-way communication with the tower 10 via, for example, aconventional wireless modem card 21 with which a wireless two-waycommunications link 9 b is established between the PC and the tower.

In this example, the server 12 is a dedicated component of the network10, while components of the cellular system, e.g., towers are operatedby a commercial provider of telecommunications services. The server 12is located in or near the command center 22 of the law enforcementoperation 6. Staff at the command center 22 perform command, control andcommunications activities typical of a law enforcement operation. One ormore computers or terminals 24 housed in the command center areconnected to the server 12 through the network 10. The computers andterminals have conventional human machine interfaces, including akeyboard, a mouse and a monitor display 26. Staff are able to monitorinformation concerning the status of the breakable link 8, madeavailable from the telephone 18 through the wireless link 9 a, over thenetwork 10 and through the server 12 to a personal computer 24 connectedto the server 12. The information is provided on the display 26 of apersonal computer 24. The mobile telephone 18 and the PC 20 areexemplary of a pair of devices having a breakable wireless link with oneanother. Specifically, in the example embodiments, these devices 18, 20each include Bluetooth communications capabilities to establish a oneway or a two-way radio frequency (RF) breakable communication link. Thetelephone 18 includes a Bluetooth transceiver 18 b and the PC 20includes a Bluetooth transceiver 20 b. For purposes of conserving power,the telephone 18 may operate in the discovery mode. The PC 20 may onlyuse transmission capabilities while the telephone 18 only uses receivecapabilities.

The telephone 18 is illustrated as the mobile client device because itis exemplary of a portable device which an officer can convenientlycarry. The PC 20 is illustrated as the stationary device because anofficer may be assigned a patrol car vehicle 28 within which such a PC20 is commonly mounted so that the vehicle is a stationary frame ofreference for the PC 20. The fact that the PC 20 is stationary withrespect to the vehicle assures that a reference position can beestablished with respect to the officer's movement away from the vehicle28. In principle, however, the mobile telephone and the computer systemcan be interchanged with one another. Moreover, each device 18, 20 maybe replaced with another kind of device, including a smart phone or atablet computer. For example, in lieu of the PC 20, hands-free Bluetoothmobile telephone equipment installed in a vehicle 28, and otherBluetooth equipment which is sufficiently stationary with respect to thevehicle frame of reference can be suitable transmitting devices. In lieuof the PC 20 any Bluetooth transmitting device may be placed in thepatrol vehicle 28 and linked to the mobile device (e.g., the telephone18) to provide a breakable RF link 8. In the illustration of FIG. 1A theBluetooth RF link 8 is shown to exist between the devices 18, 20,corresponding to a Condition One determination where an officer ispresent within or close to the vehicle 28. In the illustration of FIG.1B the Bluetooth RF link 8 between the devices 18, 20, is shown to bebroken, corresponding to a Condition Two determination where an officeris out of the vehicle 28 and more than some minimum distance from thevehicle.

In the following description the mobile telephone 18 provides a receiverrole with respect to determining whether the link 8 is broken. Accordingto embodiments of the invention, the officer has logged into the networkthrough telephone 18. The telephone 18 is mobile with respect to thevehicle 28 and is carried by the logged in (identified) officer when theofficer moves away from the vehicle. The PC 20, providing the role of astationary transmitter with respect to the vehicle 28, provides a pointof reference with respect to movement of the officer carrying thetelephone 18 away from the vehicle 20 and the PC 20. It is to beunderstood that a plurality of vehicles 28 each having a PC 20 may bedeployed in the law enforcement operation 6. The illustration of FIG. 1refers to one particular vehicle 28 to which one officer is assigned andhaving one PC 20 which is referred to as the PC 20 of interest becauseit serves as the transmitting device for the breakable link 8 with aparticular telephone 18 of interest shown in FIG. 1A.

The mobile device and the PC are “linked” by the receive and transmitfunctions of the Bluetooth transceivers 18 b and 20 b. However, inprinciple, transmit and receive functions are not needed in each of thedevices in order to determine whether or not the breakable link isbroken. In practice, the distance between the mobile unit and the PC canbe simply monitored based on the signal strength from one transmitter(in the stationary device) to one receiver (in the mobile device),rather than relying on bi-directional data communication between themobile device and the stationary device. For this embodiment theBluetooth transceiver of the mobile device may be operating exclusivelyin the discovery mode.

RF receive circuitry normally consumes much less DC power than transmitcircuitry in RF transceiver architectures. Accordingly, the Bluetoothtransceiver 20 b of the PC 20, provides the necessary transmit mode andthe Bluetooth transceiver 18 b of the mobile telephone 18 receives andprocesses the signal transmitted by the Bluetooth transceiver 20 b. Byrelying on only one device to transmit a breakable RF link signal andonly relying on the other device to receive the transmitted RF signals,power can be conserved and battery life of the telephone 18 can bemaximized. It is advantageous that the PC 20 provide the more powerconsuming role of a Bluetooth transmitter when, as is typical, the PC 20is coupled to a DC power source in the vehicle 28 instead of having torely on the limited capability of a battery to power the PC. Also, thetwo devices are not programmed to automatically “sync”. That is, in theunique context of the invention, syncing of Bluetooth devices may beeliminated to reduce power consumption. Otherwise, in the sync mode,both devices will periodically transmit signals to and receive signalsfrom one another in order to establish and maintain an activecommunication session. It can also be time consuming for the twoBluetooth devices to perform the associated protocols (e.g., handshakes)to periodically sync with one another. A data communications session isnot required to periodically determine whether the officer is outsidethe vehicle 28. Contrary to normal Bluetooth operations, only thediscovery mode need be used by the telephone 18 as this feature candetermine whether the status of the link 8 is breakable or broken.

RF signal strength of Bluetooth transmission is generally a function ofthe distance between transmitter and receiver. Friis' Free Space Lawexpresses an inverse square relationship between signal strength and thedistance between the transmitter and receiver which exists under idealconditions. The relationship is more complex in multipath environments,e.g., due to presence of reflective surfaces. The actual signal mayexhibit behavior quite different from a simple inverse squarerelationship, having nulls and peaks which are difficult to predict as aresult of the multipath combinations. Even though a Bluetooth signal mayexperience multiple reflections in the environment in or about a vehicle28, the inventors have found that the RF signal quickly decays as ittravels from the transmitter location to a receiver location outside thevehicle. Accordingly, the relationship between signal strength anddistance from a Bluetooth transmitter may be relied upon to indicatewhether a receiver has exceeded a minimum distance from the transmitter.In part, the invention is based on recognition that a relatively rapidsignal decay rate can be observed in signal propagation environments(e.g., within the vehicle 28 or in the immediate vicinity of thevehicle) which are not very predictable. While an environment ofmultiple reflective paths results in unpredictable signal levels, e.g.,due to varied ray paths, the variability in signal strength can betolerated because sufficient overall signal attenuation occurs overdistances of two to six meters such that the actual attenuation can beused to indicate when distance between a source and a receiver exceedssome minimal value. A drop in signal strength below a minimum value cantherefore reliably indicate whether the location of the receiving device(e.g., the mobile telephone 18) is outside of and/or some distance awayfrom the vehicle 28.

In one implementation the Bluetooth transmitter of the PC 20 of interestis always transmitting when the PC 20 is operating, and the Bluetoothreceiver in the telephone 18 is always in an active mode to receive thesignal transmitted from the PC 20 of interest. With the PC 20 acting asa stationary beacon to the mobile telephone, the integrity of systemoperation requires that the PC 20 of interest not be moved away from thevehicle. When the vehicle is a patrol car, some movement of the PC 20within the vehicle compartment may be tolerable. On the other hand,movement of the PC 20 to a position which significantly changes signalpropagation characteristics should be avoided.

In order to provide reliable information about the condition of abreakable RF link of interest (e.g., between one mobile telephone 18 andone PC 20), it is important that the receiving device discriminatebetween the signal transmitted from the PC 20 of interest and one ormore other signals transmitted from Bluetooth sources other than the PC20 in a particular vehicle 28. Otherwise, when the mobile telephone ispositioned a sufficient distance from the PC 20 to break the link ofinterest, the telephone 18 may indicate otherwise, i.e., providing afalse positive indication of a Condition One based on an unintendedreceipt of a relatively strong signal from a different Bluetoothtransmitting source.

One method of discriminating between receipt of an intended RF signaland other signals is to identify the intended signal based on the MACaddress of the PC 20 of interest. More generally, the telephone 18 maybe provided with a listing of MAC addresses for all PC's deployed in allvehicles 28 in the particular law enforcement operation 6. The listingof addresses includes an association of the MAC address of each PC 20with a specific vehicle 28 in which it is positioned. The telephone,operating in the discovery mode, can check each MAC address for whichthere is a signal that exceeds a specified minimum power level and thenidentify the signal as being of the first condition, i.e., detectable,in accord with Condition One, along with an identification of theassociated vehicle 28. The listing of MAC addresses may be downloaded tomemory or storage media in the telephone 18 or the telephone 18 mayaccess the information from the server 12.

A feature of using such a look-up table is that the method can bereliably deployed to identify the second condition, i.e., a ConditionTwo (e.g., in which a breakable link previously found to be a ConditionOne has transitioned to being a broken link) in a variety of situations.For example, the method can be readily applied when multiple officershave entered the same vehicle 28 even through the particular vehicle isonly assigned to one of several officers. When multiple officers aresimultaneously in the same patrol vehicle, the method can assure thereis a responsive link between each of multiple telephones 18 assigned todifferent officers and the one PC 20 of interest having a MAC addressassigned to that same vehicle. Consequently, movement of each officerout of the vehicle 28 can be detected. Further, after the responsivelink is assigned between the PC 20 in one vehicle (based on a temporarypresence of an officer in or near that vehicle), subsequent movement ofthat officer out of that one vehicle and into another vehicle results inestablishment of a new link between the same telephone 18 and a PC 20having a different MAC address.

The method provides situational awareness of whether and when an officermoves between patrol vehicles. For example, it is possible to knowwhether an officer has simply exited a patrol car or has moved from onepatrol car to a different patrol car. Based on changes in MAC addresses,the method provides knowledge of which patrol vehicle an officer is inor near, even though the officer has moved away from an assignedvehicle.

Most devices which receive Bluetooth RF signals have a Receive SignalStrength Indicator (RSSI) which is an indication of an RF received powerlevel, i.e., a measurement of the power of a signal received fromanother Bluetooth device. For embodiments of the invention thisindicator is used to determine when the officer is out of the patrolvehicle 28. In one embodiment RSSI values can be monitored to determinewhether the signal strength has diminished to a level which iseffectively “no signal” as might be indicated by a threshold level dropin signal power by, for example, 80 dB. According to such an embodiment,when an officer has exited the vehicle 28, the RSSI value can be reliedupon to decay substantially, e.g., by 80 dB. This drop in RSSI value isreferred as a “link broken” condition or a broken link.

The exemplary 80 dB threshold decay may be based on a predetermined andtypical RSSI decay value observed for all PC's 20 in the law enforcementoperation 6. Alternately, the threshold decay level may be based on asignal power drop relative to a RSSI value registered when the telephone18 is located inside of a patrol car. Although a decay of 80 dB may beused as a criterion in the illustrated embodiments to establishexistence of a broken link 8, other levels of decay can be used as thecriterion for determining whether there is a broken link 8, e.g., RSSIlevel drops of 40, 50, 60, 70, 90 or 100 or more dB. Further, othermetrics than RSSI may be used to establish whether there is a brokenlink. Also, when the vehicle 20 is not a patrol car (e.g., the vehicle20 may be a motorcycle) a smaller decay threshold may be suitable toindicate that the officer has walked a minimum distance away from thevehicle, e.g., two to six meters.

In applications which monitor whether an officer is outside of a patrolcar, the distance at which the RSSI value decays by 80 dB can be in therange of 2-3.5 meters, depending on the physical properties of thetransmission path between the transmitter and receiver. For example,propagation and attenuation characteristics may vary depending onwhether vehicle windows are tinted, and whether roll-up windows are inup or down positions, and environmental conditions. For example,precipitation can alter the rate of attenuation of a wireless RF signal.When the RSSI value increases from the exemplary 80 dB threshold ofdecay, the link is deemed to be re-established and it is assumed thatthe officer is either positioned inside the vehicle or close to thevehicle. Receiving such a signal may be interpreted as an indicationthat the officer is not presently handling a policing matter or that theofficer is near the safety of his vehicle and is available to respond toa request or receive instructions from the command center 22.

The server 12 hosts a first application 34 for monitoring the status ofthe breakable link in coordination with a second application 38 runningon the mobile telephone 18. The second application programs thetelephone 18 to communicate with the server 12, via a wireless link 9 aand the cellular system 14 and the internet. Communications between thetelephone 18 and the server 12 include transfer of information relatingto the status of the link 8. The telephone 18 may also receive otherinformation from the server 12, such as alerts regarding the status ofother links between other telephones or hand held devices and stationaryBluetooth devices in other vehicles 28, e.g., other PCs 20. As long asthe mobile telephone has a wireless connection to the internet, thestatus of the breakable link 8 (i.e., whether Condition One or ConditionTwo exists) is relayed to the server 12 and can be monitored by staff onthe display 26 at the command center 22.

In one implementation the mobile client device, e.g., the telephone 18or a different type of Bluetooth enabled hand held device, is also GPSenabled. The application 38 running on the mobile device obtainsposition data which is provided to the server application 34 via thewireless link 9 a, in conjunction with the status of the breakable linkto identify the location of the officer. The server 12 then graphicallydisplays in real time both the officer location and the location of thevehicle 28 on a map shown on the display 26 of the computer 24 in thecommand center 22. For example, the screen of the display 26 may showonly one icon, corresponding to the vehicle 28, when the officer isinside the vehicle, and show two icons when the officer has exited thevehicle, with one icon representing the vehicle 28 and the other iconrepresenting the officer positioned outside the vehicle. In anotherembodiment, two different colored icons may be used to display thevehicle, depending on the state of the breakable link, e.g., blue forwhen the officer is inside the vehicle 28 and red for when the officeris out of the vehicle.

According to a power conserving option, with the GPS receiver used toindicate an actual position of the officer (or a distance between theofficer and the vehicle), both the GPS receiver and the Bluetoothreceiver in the mobile telephone 18 may be turned off when the officeris more than a minimum distance from the vehicle, e.g., at least fourmeters from the vehicle. Another advantageous feature, resulting fromcontinual provision of position data in conjunction with the status ofthe breakable link to the server application 34, is that the location ofthe vehicle 28 can be determined based on, for example, comparison ofposition data acquired immediately before the link 8 is broken withposition data acquired after the link 8 is broken. Further, the relativedistance between the vehicle and the officer in possession of the mobiletelephone 18 can be determined.

When the RF link 8 is broken the server application 34 can initiateoperation of an electronic timer. Timer operations may reside in thetelephone 18, in the server 12 and even in the personal computer 24. Forexample, the timer may be a simple subroutine function in the mobiledevice application 38 or the server application 34 which includes acounter function based on a clock signal. Output from the timer can becommunicated from one device to another device over the network 10.Timer functions are useful for periodically acquiring link statusinformation, position information and determining whether an officer isaway from a vehicle more than a pre-determined time. As alert isgenerated when the lapsed time exceeds the predetermined value, based onan assumption that if the officer does not return to the vehicle withinthe predetermined time period there is reason to suspect that theofficer may be in trouble. The alert may originate in the server 12 ofthe personal computer 24 or may otherwise be sent to the command center22 or the server for dissemination to other officers. The alert may besent to a selected array of devices (e.g., PCs in other vehicles 28 andhand-held devices such as mobile telephones carried by other officers).However, when the officer re-enters the vehicle 28, as confirmed by thelink exhibiting at least the minimum power required for a Condition One,the timer operation is canceled and an update is broadcast to a selectedarray of client devices to communicate to other officers that the alertis removed. Command center personnel at various locations could haveauthority to remove the alert remotely if it is determined that theofficer is not in any peril requiring a response.

According to a general method implemented in the exemplary lawenforcement operation 6 shown in FIG. 1, the Bluetooth wireless link 8is established between the PC 20 of interest and the mobile telephone 18wherein the PC 20 provides the necessary transmitter function to beacona signal within and outside of the vehicle 28. Based on the signalattenuation characteristics, the useful Bluetooth transmission distanceof the signal is limited to distances relatively close to the vehicle,e.g., a few meters. Consequently, when the vehicle is a patrol car andthe mobile telephone 18 is located in a vehicle 28, the application 38running on the telephone 18 periodically provides Condition Onenotifications to the server 12 that the RF link is operational, i.e.,that the receiving device (e.g., the telephone 18) is receiving apredefined minimum power level.

Because the telephone is normally carried by the officer, when theofficer steps out of the vehicle 28 and moves away from the vehicle, thetelephone 18 is carried away from the vehicle 28. Thus at some thresholddistance of separation between the telephone and the vehicle 28, thewireless link 8 between the telephone 18 and the PC 20 breaks. That is,the RSSI level decays to or below a predetermined value. When thishappens the application 38 running in the telephone 18 notifies theapplication 34 running in the server 12 of a Condition Twodetermination, that the previously established breakable link 8 isconsidered broken because it no longer exhibits a minimum power level.See, again, FIG. 1B. Subsequently the timer routine is initiated by theapplication 38. As long as the link 8 is broken, the Condition Twonotification remains, i.e., a flag is set, indicating that thepreviously existing link 8 remains broken and the timer value iscontinuously updated until the flag is removed. Whenever the server 12receives a notification that there has been a transition betweenCondition One and Condition Two, the server 12 updates statusinformation relating to the officer and the patrol vehicle 28 in a database 40. For each transition from Condition One to Condition Two, theserver 12 provides this information for viewing on the display 26 tonotify staff at the command center 22 of the current status of theofficer. Following a Condition Two determination, and initiation of thetimer routine, when the timer reaches a predetermined threshold, theserver also broadcasts an alert 42 to all stationary devices (e.g., PCs20) positioned in all vehicles 28 and to all hand held devices (e.g.,mobile telephones 18) carried by officers in the law enforcementoperation 6. See FIG. 1C. The alert 42 is a cancelable notification thatthe officer associated with the hand held device (e.g., telephone 18) isoutside of or away from the vehicle 28. The alert 42 is only sent whenthe time exceeds a certain threshold. The map and timer are periodicallyupdated on all telephones 18 to provide continual situational awareness.

For each transition from Condition Two back to Condition One, the serverbroadcasts a cancelation of the alert 42 to all stationary devices andall hand held devices. The cancelation of the alert 42 indicates thatthe officer has returned to or entered into the vehicle 28. As noted,when the RF link 8 is broken an electronic timer can be started. Forexample, at the time the alert 42 is sent to the server 12 at thecommand center 22 the timer can be initiated by the server application34. If the lapsed time exceeds a predetermined value before the alert 42is canceled, the server provides this information as a higher levelalert 44 on the display 26 to notify staff at the command center 22 of apotential danger or risk of safety to the officer associated with thealert 42, and the server also broadcasts (initiates) the higher levelalert 44 to all stationary devices and all hand held devices carried byofficers in the law enforcement operation 6. See FIG. 1D. In otherimplementations, the alerts 42 and 44 may each be broadcast to selectedsub-arrays of devices. For example, alerts may only be made availablethrough hand-held client devices being carried by those officers whoare, at the time, within a given distance from the location of thevehicle 28 associated with the alerts 42 and 44.

FIGS. 2A-2C illustrate a log-in sequence, a monitoring routine and alog-off sequence according to a method of the invention in the network10. The term log-in refers to a common computer security process inwhich a user logs in or on or signs in or on to, for example, a computersystem, by which process the user attains individual access to thesystem or to an application or a specific page. The log-in process mayinclude both identification and authentication of the user based oncredentials. A user can also log out or off to remove access to thepage, application or system.

With reference to FIG. 2A, an officer initially logs into the telephone18, opens the application 38 and logs into the network 10 through theapplication 38 running on the mobile telephone 18 (Step 1). Log-in tothe server occurs, for example, when the officer comes on duty orassumes operation of a vehicle 28. The log-in sequence queries the useras to whether the mode of transportation will be a vehicle 28 having aknown MAC Address for a RF device suitable for establishing thebreakable link 8, such as a patrol car (Step 2). If the officer responseis negative, the log-in ends (Step 3). If the officer response isaffirmative, the application 38 places the telephone 18 in the BluetoothDiscovery Mode (Step 4) in order to find a Bluetooth signal from a PC 20or other stationary device within in the vehicle 28 and which isincluded on the list of authorized Bluetooth MAC addresses in the database 40. If, in response to an inquiry as to whether an authorizedBluetooth MAC address is found (Step 5), there is an affirmativedetermination, then (Step 6) the mobile telephone 18 stores theBluetooth MAC address of the PC 20 or other device which is in theparticular vehicle 28 being used by the officer. If no authorized MACaddress is identified by the mobile telephone 18, the application checksto determine whether a notification has already been sent to the displayof the telephone 18 to advise the officer that no authorized PC 20 hasyet been found (Step 7). If no such notification has been sent to thetelephone display a notification is sent to the display to advise theofficer that the telephone 18 is not yet linked to any Bluetooth enableddevice having an authorized MAC address (Step 8). After the notificationis sent (Step 8) the application cycles through Steps 4, 5 and 7 until aPC having an authorized MAC address is found. Once an acceptable PC 20has been identified, a link 8 is established and the application 38stores the MAC address of the PC 20 which has the link with thetelephone 18 (Step 6).

Referring next to FIG. 2B, with the link 8 established, the telephone 18cyclically checks the Bluetooth RSSI level for the PC 20 having thestored MAC address (Step 9) and so long as the signal power remains atleast 80 dB above a minimum value, e.g., a threshold power level, theapplication provides a determination that the Condition One statusexists. To effect this determination, an inquiry is periodically made asto whether the RSSI level of the link 8 has dropped at least 80 dB,e.g., relative to a RSSI value registered when the telephone 18 islocated inside of a patrol car. (Step 10) In other implementations, the80 dB drop may be relative to a prior measured RSSI level or relative tosome average RSSI level. The RSSI value is continually updated on thetelephone 18. It may be an intrinsic value generated by circuitry whichprovides the Bluetooth functionality. If the RSSI level has notundertaken, for example, an 80 dB drop the periodic inquiries continue.If the RSSI level does drop by, for example, at least 80 dB, thetelephone 18 transmits a command to the server 12 to update the statusinformation (Step 11) concerning the officer. In response the serverchanges the status of the officer in the data base 40 from an “Officerin Vehicle” (OIV) Condition One status to an “Officer Out of Vehicle”(OOV) Condition Two status (Step 12). The server 12 also broadcasts the“Officer Out of Vehicle” Condition Two status to all stationary devicesand all hand held devices carried by officers in the law enforcementoperation 6 (Step 13).

While the OOV Condition Two status exists, the application 38 running inthe telephone 18 continues to periodically check the RSSI level of theBluetooth signal received from the MAC address of the authorized PC 20(Step 14). The application determines whether the RSSI level hasincreased to a level above the previously observed drop in signal powerlevel of, for example, at least 80 dB (Step 15). If there has not been arecovery which brings the signal power level above the previouslyobserved drop of at least 80 dB, the application continues toperiodically check the RSSI level (Step 14) and determine whether theRSSI level has increased to a level above the previously observed dropin signal power level of at least 80 dB (Step 15). If there is adetermination that the RSSI level has increased above the previouslyobserved power level drop of at least 80 dB, the phone 18 transmits acommand (Step 16) to the server 12 to change the status of the officer,in response to which the server updates the data base 40 (Step 17) froman OOV Condition Two status to an OIV Condition One status. When theCondition Two status transitions to the Condition One status the server12 also cancels any Condition Two status alerts 42 which werebroadcasted to the stationary devices and hand held devices carried byofficers in the law enforcement operation 6 (Step 18). After step 18,the cyclic monitoring process then continues at Step 9. In an alternateembodiment, the application 38 implements Step 15 to determine whetherthere is a transition from Condition Two to Condition One by determiningwhether the RSSI level has increased to a level at least 10 dB above thepreviously observed drop in signal power level of at least 80 dB. Thatis, according to the alternate embodiment, a threshold measured RSSIvalue required for transition from Condition Two to Condition One is 10dB higher than the threshold measured value required for transition fromCondition One to Condition Two. Having a somewhat higher transitionthreshold for recovery to Condition One helps avoid an intermittentfluctuation around the 80 dB, e.g., if the officer is still outside of apatrol car in which the PC 20 is situated.

Referring next to FIG. 2C, when the officer logs off of the server 12(Step 19) the system queries whether the officer is out of the vehicle28 at the time of log-off (Step 20). If the officer is out of thevehicle 28 at the time of logging off of the server 12, any existingalerts 42, 44 are canceled (Step 21). If the officer is in the vehicle28 when logging off of the server 12, there is an OIV Condition One linkstatus and the link 8 is deactivated (Step 22). In any case, afterlogging-off of the server, the MAC address of the PC 20 (or otherBluetooth device) in the vehicle with which the link 8 is established isremoved from the telephone 18 (Step 23). The application 38 and relatedservices are then terminated (Step 24).

Generally, there has been described a method for determining theposition or location of a person relative to a rf source positioned, forexample, in a vehicle. A series of embodiments employs at least threedevices: (i) a mobile client device such as the telephone 18, runningthe software application 38, also referred to as mobile client software;(ii) a device, stationary relative to a vehicle frame of reference, suchas the PC 20, which transmits rf signals for receipt by the clientdevice, and (iii) a server such as the server 12, which runs thesoftware application 34 to improve situational awareness of deployedofficers by exchanging information with the mobile client devices, e.g.,via a network including a cellular telephone system. There are twostates that can be assigned to the mobile client device: the Officer Invehicle (OIV), Condition One, in which the client device is in orproximate the vehicle or very close to the stationary device; and theOfficer Out of Vehicle (OOV) Condition Two, in which the client deviceis relatively far from the stationary device. In the context of thedescribed law enforcement operation, a Condition Two at least results inan Alert 44 which is a first notification that an officer is away from avehicle. A Condition Two may also result in a second Alert 48 whichnotifies others that the officer has been away from the vehicle forlonger than a predetermined time period, thereby alerting personnel thatthe officer may be having trouble.

In an embodiment applicable to the afore described law enforcementoperation 4, the method for determining the position or location of anofficer relative to a vehicle 28 (or a stationary rf source in thevehicle) is performed in the network 10, with the software application34 running on the server 12 and the software application 38 running oneach client device (e.g., telephones 18 or other hand held devices)which officers on duty have used to log into the network 10. A series ofcomponent processes is illustrated in FIG. 3. Each of the client deviceslogged into the server 12 periodically provides updates to the server 12regarding the status of the officer, i.e., whether the officer is in anOIV Condition One state or an OOV Condition Two state. Each time anupdate is received the server writes the periodically provided statusinformation to memory and to the database 40. The server 12 alsobroadcasts information (e.g., in the form of alerts 44 or removal ofalerts), regarding transitions between OIV and OOV conditions for eachofficer who has logged into the server application 34. Whenever theserver receives information that an OOV Condition Two exists for anyofficer, the server application 34 initiates a timer function for thatofficer. If the link for an officer is determined to be in a ConditionTwo OOV status for a lapsed time which exceeds a predefined period, asmeasured with the timer, an alert 48 is broadcasted through the network.On the other hand, whenever the status of an officer reverts from an OOVCondition Two to an OIV Condition One, and the predefined time periodhas not yet lapsed, operation of the associated timer function iscanceled.

For each client device logged into the software application 34, theclient device utilizes a second timer function running, for example, onthe client device, to periodically request from the server application34 at, for example, three second intervals, a most current list of othermobile client devices and/or names of officers associated with othermobile client devices that are within a measured distance or within adefined zone. The server then issues a message containing the requestedlist of officers. In addition to the names of officers, the list mayalso include locations (e.g., based on GPS location data) of theofficers and a most recently updated link status for each officer (e.g.,as to whether the link status of the listed officer is a Condition Oneor a Condition Two). Once each mobile client receives the list of nearbyofficer information, the client device updates an internal list ofofficers based on the received information. If the application 34running on the mobile device provides for graphic display of nearbyofficers (e.g., on a geographic map), the status of each officer isindicated in the form of icons or other means to show, for example, anOOV status.

Several subroutines according to exemplary implementations of theinventive concepts are illustrated in simplified flow charts shown inFIGS. 3 and 4. Although the subroutines are illustrated as discretefunctional blocks, such representations are provided to illustratefunctionality. Actual implementations may be had in numerouscombinations including integration of specific functions or tasks thatare illustrated in different flow charts. The example assumes thatmultiple officers are simultaneously logged into mobile client devicesand the applications 34 and 38 are continuously running on the clientdevices and the server, respectively. With reference to FIG. 3A, aprocess for monitoring situational awareness is initiated in each clientdevice with an officer performing a secure login process as summarizedin subroutine 310. Each officer uses an assigned mobile client device(e.g., a telephone 18) to simultaneously log into the client device andthe server 12 via the network 10. Once the officer is logged into thenetwork server, multiple client functions are initiated on the clientdevice in cooperation or coordination with functions running in theserver application 34. Subroutines 320, 330, 340, 350, 410 and 420 areexemplary of functionality implemented by the applications 34 and 38.

Client subroutine 320, shown in FIG. 3B, runs on the client device tocontinually determine the status of the breakable link 8. See, also,client subroutines 330, 340 shown in FIGS. 3C and 3D, and serversubroutine 410 illustrated in FIG. 4A. Link status determinations andofficer location information are periodically updated in memory orstorage locations (internal state) in the mobile client device. Theclient device accesses this data to report the updated statusdeterminations and location information to the application 34 running onthe server 12. With further reference to FIG. 3B, after the mobileclient device is logged in to the server under a Condition One, a valueof the RSSI level associated with the Bluetooth signal transmitted fromthe officer's vehicle, as measured by the client device, is read fromthe Bluetooth circuitry. The value may be referred to as a pre-existingvalue if it is used as a level relative to which signal decay ismeasured when the mobile client device is moved away from the officer'svehicle in which the stationary rf transmitting device (e.g., a PC 20)is fixedly positioned. A timer function is also initiated in the mobileclient device. The timer function periodically resets to a counter startvalue and is decremented in accord with a clock signal to, for example,periodically indicate lapsed time periods of sixty second duration. Eachtime the counter value reaches zero, indicating that a predefined timeinterval (e.g., sixty seconds) has lapsed, a comparison is made betweenthe pre-existing value and a newly acquired RSSI value of the Bluetoothsignal transmitted from the officer's vehicle, as measured by the clientdevice. The pre-existing value may be a value other than the RSSI valuemeasured immediately after the client device is logged in to the serverunder a Condition One. The difference between the pre-existing value andthe newly updated RSSI value is used to determine whether a ConditionTwo (broken link status) exists. The criterion for establishing that aCondition Two exists is whether the most recently measured RSSI level isless than or equal to a defined minimum value which is based in part onthe pre-existing value. If the difference between the most recentlymeasured RSSI level and the pre-existing value exceeds the definedminimum value, the OOV Condition Two is deemed established. Summarily,the difference between the pre-existing value and the newly updated RSSIvalue of the Bluetooth signal may be compared to the threshold value todetermine whether an OIV Condition One or and OOV Condition Two linkstatus exists. Each time the difference is computed and the link statusis determined, the subroutine 320 sets a flag indicative of thedetermination.

With reference to FIG. 3C the client subroutine 330 utilizes the timerfunction of client subroutine 320 to (i) periodically acquire thephysical location of the officer based on, for example, GPS dataacquired by the client device, and (ii) periodically obtain a currentlink status determination provided by the subroutine 320. With thecounter set to a start value determinative of the predefined timeinterval, e.g., sixty seconds, the updated status of the link 8 (i.e.,OIV Condition One or OOV Condition Two) and the updated location of theofficer are periodically written to memory or storage. The updatedstatus of the link is based on the most recently determined differencebetween the pre-existing value and the updated RSSI value. For example,on each occasion the counter value reaches zero, after the flag settingis updated to indicate the link status determination, the subroutinewrites the most recently updated information in memory or storage media.

This periodically updated stored information is available for access inorder to routinely send current information on link status and officerlocation to the server. At least whenever the client device determinesthat a transition has occurred between a Condition One link status and aCondition Two link status, the client subroutine 340 updates the officerlocation and the status of the logged in officer on the server. That is,a request object can be populated based on the information stored inmemory. Alternately, each time the timer value is decremented to zero,the client device may send the officer location and link status to theserver 12. The received information is used as an update to theofficer's status and location information stored in the server database40. Each update may provide the same status information as animmediately preceding update or may provide changes to the statusinformation.

In the foregoing example, the client device provides updated informationto the server. Generally, the client device may provide information toor request information from the server. When providing information tothe server, such as an update to the officer's current location, theclient device generates a Java request object, adds the current officerlocation information to the object, serializes the request object (i.e.,the request object undergoes Java object serialization) and sends it tothe server. Upon receipt, the server deserializes the data and updatesthe database 40 accordingly. The server then sends an empty Javaresponse object to the client device. Upon receipt of the responseobject the client device closes the HTTP connection with the server.

A component software module of the client application 38, referred to asthe Adjacent Officer Manager Service, runs in the background of theclient device, periodically acquiring updates of information from theserver. A process for generating and receiving requests for data, e.g.,status and location updates for nearby officers, also involvesgenerating a Java class “request object”.

The Adjacent Officer Manager Service periodically requests updates for alist of nearby officer information for display on the client device. Therequested updates are based on information periodically received by theserver from each officer logged into the server application 34. See FIG.3D in which subroutine 340 [FORMERLY CLIENT PROCESS 4] illustrates anexample process for graphically displaying the status of the link 8 forother officers near a particular officer's mobile client device.

In order for the client device to obtain a list of nearby officers fromthe server, the client device generates a Java request object (i.e.,that the server provide the list), serializes it and sends it to theserver. Upon receipt, the server deserializes the request object andqueries the database to identify nearby officers (according to specifiedcriteria such as distance from the client device making the request).The server then builds a Java response object, populates it with linkstatus and location data, serializes it and sends the response object tothe client device which generated the request object. The client devicedeserializes the response object, closes the HTTP connection andprocesses the list of officers, e.g., to generate and display a list ora map of officer locations.

The client subroutine 350 of FIG. 3E illustrates a generic process inwhich the client device initiates data requests and receives data fromthe server. The request object is serialized, e.g., undergoes Javaobject serialization, and is assembled in memory as a data sequence oris stored as a file descriptive of the object and object type. Objectserialization converts the message request so that it can be transmittedthrough an open network socket created by the client device and acrossthe network 10 to the server 12 for receipt in the application 34. See,also, FIG. 4B in which the server subroutine 420 receives and respondsto a request from one of multiple client devices for a most current listof nearby officers and associated graphic display data. When the mobileclient devices request updated lists of nearby officers from the server,the information is used to update maps on the mobile devices, displayedlists of officers, and other components of the application 38 whichutilize this information. This allows the mobile client devices todisplay timely information as to which officers are away from assignedor designated vehicles. Any client screens that display a list or map ofother officers can be updated to display such officers in anidentifiable way as being away from designated vehicles.

Once received by the server 12, the serialized message data isdeserialized and reconverted into a Java request object for the serverapplication 34. After the message is accepted by the server as a validrequest, the server generates a list of logged in users from currentinformation in the database 40, complete with the location and status ofeach officer. The list may be customized to limit the number of officersbased on designated criteria, e.g., whether each officer is within acertain distance of the client device making the request. The serverthen creates a “response object” which is populated with a list ofofficers consistent with specified criteria, e.g., desired radius fromthe location of the requesting client device. The criteria may be set bythe officer logged in to the client device. The server may also generateand populate the response object with image data that graphicallyillustrates relative locations of listed officers on maps (e.g.,referred to as a map screen or a radar screen in client subroutine 340).However, such image data may be generated by the client device whichreceives the response object. The response object is serialized and sentback through the network socket on the server, across the network, andthrough the network socket on the client. The client device thendeserializes and processes the data for display on the client device.

With further reference to FIG. 4A, upon receiving a request object froma client device containing an update to the link status, the serversubroutine 410 updates the link status of the particular client devicein the database 40. When the updated link status of the associatedofficer is an OOV Condition Two, a timer function resident in the serveris initiated which will cancel if, during a designated time period, theofficer returns to the vehicle, thereby once more creating a ConditionOne status. If the timer is not reset by the end of the designated timedperiod, an alert 44 is generated by the server 12 to advise others ofthe officer's OOV status. The alert is then broadcasted to announce thata specific officer has been out of a vehicle for too long. Any mobileclients then requesting an updated list of officers will receive thealert 44, indicating the current status of the officer as havingtransitioned from an initial OOV Condition Two to an alert advisorystatus because the officer has been away from the vehicle for a timeexceeding the designated period.

FIG. 5 provide an exemplary sequence of illustrations showing thedisplay of a hand-held device, such as the mobile telephone 18,according to an embodiment of the client application 38 running on thetelephone 18. The sequence begins with display of a conventional gesturelog-in screen having a pre-defined log in combination for a new user asshown in FIG. 5A. Once the new user logs in for the first time, the useris prompted to change the log in pattern from the pre-definedcombination to another combination as indicated in FIG. 5B. Next,referring to FIG. 5C, the new user is prompted to select a Nickname anda Call Sign. The user may also add a picture. Once logged into thesystem, e.g., the hand-held device and the server, the user is taken tothe menu screen shown in FIG. 5D. An upper row having three buttonsprovides situational awareness functionality in which the user mayselect presentation formats including (from left to right) an OfficerList, a satellite view or street map view (not shown) or a Radar view.

The officer list presentation format shown in FIG. 5E provides names ofall officers logged into the server sorted by distance from the user'stelephone 18. This presentation format includes the officer's name, apicture, each officer's transportation mode and the call sign of theofficer. The transportation mode is indicated by icons such as: a patrolcar, a person on foot, a motor cycle, a bicycle or a horse.

In another display format, all logged in officers are displayed on a mapscreen as icons with their call signs. See FIG. 5F. The screen caneither provide a satellite view or a street map view (not shown). Whenan icon is clicked, the system will display a pop-up containing the nameand a picture of the officer as shown in the figure.

FIG. 5G illustrates display of a close-in Radar screen view of allofficers within 1500 m of the user telephone 18, with the userpositioned as though it is a radar beacon. The 1500 m range may beadjusted to a smaller radius by the user sliding a finger up and down onthe screen. The radar view may be coupled to a phone compass to rotatethe view about the telephone 18 and provide a correct orientationrelative to true north, or to provide other desired orientations.

A single officer may be selected for display on a map, either from theofficer list of FIG. 5E or from a map view, e.g., FIG. 5F (in streetview or satellite view), by double clicking on an icon. The map onlyshows the positions of the user and the one officer the user hasselected. This reduces clutter on the screen and renders it easier tolocate the selected officer on the display. A button at the bottom ofthe screen enables the user to toggle between one of the map views andthe radar view shown in FIG. 5I.

A system and a method have been described which can improve situationalawareness of a person in possession of a handheld device having a linkto another device. One of the two devices has a communications link overa network to a computer. The mobile client device may be a smart phone,e.g., such as the telephone 18, or a tablet computer including, but notlimited to devices utilizing an Android operating system.

Although only a few example embodiments of the invention have beendisclosed, many other embodiments will be apparent. For example, in lieuof providing an application in the mobile telephone 18 to determinewhether a breakable link is broken, such a mobile application couldreside in the PC 20 or in another beacon device having a stationaryposition within the vehicle 28 frame of reference. Execution of theapplication within the device which remains stationary with respect tothe vehicle can perform the same function as a similar applicationrunning in the mobile telephone 18 or other hand held device. Further,two similar applications can run simultaneously (e.g., one in thetelephone 18 and one in the PC 20) to provide for a level of redundancy.In this regard, there may be occasions when the stationary device (e.g.,the PC 20) has a better connection to the network 10 than the devicecarried by the officer. When using the stationary device to transmitsituational awareness information to the server 12, the stationarydevice may still be the transmitter and send information based onreceipt of information from the portable device. In other embodiments,the stationary device may be the receiver running an application whichsends an alert if a link has been broken. This may be a preferredarrangement if there is concern that situational awareness informationabout an officer carrying a hand held device may be lost if only thehand held device provides information to the server 12. It is also notedthat when more than one person becomes associated with the same vehicle(e.g., when two or more officers are riding in the same patrol vehicle),a breakable link can be established between each telephone 18 (or otherhand held device) in the possession of each person in the vehicle andthe same PC 20 in the vehicle.

When implementing methods according to the invention, it will berecognized that different Bluetooth transceivers may exhibit significantvariations in transmitted signal strength and signal detectionsensitivity, e.g., on the order of 3 dB, and such variations may need tobe accounted for in order to provide consistent determinations of OIVand OOV status.

The disclosed methods may be applied to determine how many times anofficer enters and exits the vehicle while on duty. This information canbe correlated with reported activities such as traffic stops and trafficcitations issued during the officer's shift. By monitoring the averageamount of time the officer is outside the car, it is, for example, toassess efficiency and effectiveness of an officer. The invention may beadvantageously used in a variety of applications where security andsafety of the person are to be monitored. The invention is alsoadvantageously used when multiple persons are deployed in a fieldoperation in order to conveniently assess the availability, location orstatus of individuals without having to initiate voice communications.

Although examples of the invention have been provided in the context ofa law enforcement operation, methods and systems according to theinvention could be applied to many other applications, includingsecurity operations, military operations and commercial contexts such asmonitoring whether a driver of a transport vehicle has stepped out ofthe vehicle. Further, although the invention has been described in thecontext of a car, other types of vehicles, including motor cycles, canbe provisioned with a Bluetooth transmitter in the vehicle frame ofreference to provide improved situational awareness of an officer orother personnel based on movement away from the vehicle.

Accordingly the scope of the invention is only limited by the claimswhich now follow.

The claimed invention is:
 1. A non-transitory computer readable mediumcontaining program instructions representing software executable in acentral monitoring system comprising a computer system including amicroprocessor memory media and storage media and connected to anetwork, which instructions, when executed by the computer system, causethe computer system to perform method steps for monitoring the status ofmultiple persons in a group based on distance between a communicationsdevice associated with each person and one of multiple vehicles, eachperson in the group associated with one of the vehicles, the statusindicative as to whether each person in the group has moved away from anassociated vehicle or returned thereto, wherein each communicationsdevice is a first device in a pair of first and second devices, thefirst devices being carried by persons in the group while the seconddevices are each positioned at one of the associated vehicles, themethod comprising: receiving, by a central monitoring system comprisinga processor, digital data from at least one member in each pair ofdevices in communication across a network with the processor of thecentral monitoring system, and processing the digital data received fromthe at least one member in each pair of devices, by: identifying eachcommunications device in each pair of devices; associating thecommunications device in each pair of devices with a person in the groupwho is assigned to the communications device; assimilating locationstatus information from the data received from at least one member ineach pair of devices, wherein the data is based on a distance betweenthe devices in each pair derived from strength of a RF signaltransmitted from one device in the pair toward the other device in thepair, the location status information indicative of persons in the groupbeing in a first status when the person associated with thecommunications device in the pair has moved beyond a predetermined rangeof distance from the vehicle; and outputting updated location statusinformation to a display screen to provide notification when a person inthe group is in the first status.
 2. The non-transitory computerreadable medium of claim 1 wherein execution of the program instructionsby the computer system causes the computer system to receive the digitaldata from the at least one member in each pair of devices via a wirelessnetwork.
 3. The non-transitory computer readable medium of claim 1wherein the program instructions when executed by the computer systempopulate a data base that associates each portable device with a personassigned thereto.
 4. The non-transitory computer readable medium ofclaim 1 wherein the program instructions, when executed by the computersystem, associate the communications device in each pair of devices witha person in the group who is assigned to the communications device byaccessing a database that associates each portable device with arespective person assigned thereto.
 5. The non-transitory computerreadable medium of claim 1 wherein, according to execution of theprogram instructions, the step of receiving digital data, includingassimilating the data, is performed periodically to automatically placestatus information in a database and periodically update the database toprovide new status information regarding movement of each person in thegroup with respect to an associated vehicle.
 6. The non-transitorycomputer readable medium of claim 5 wherein, according to execution ofthe program instructions, the step of outputting location statusinformation to a display screen to provide notification when a person inthe group is in the first status is performed periodically to provideupdated location status information to the display screen.
 7. Anon-transitory computer readable medium containing program instructionsrepresenting software executable in a central monitoring systemcomprising a computer system including a microprocessor memory media andstorage media and connected to a network, which instructions, whenexecuted by the computer system, cause the computer system to performmethod steps for monitoring whether one or more persons in a group haveeach been away from an associated vehicle for longer than apredetermined time period, comprising: receiving into the computersystem an association between each of multiple persons in the group witha vehicle; automatically receiving into the computer system digitalinformation, derived from measured rf signal strength and sent via thenetwork, indicating whether any one of multiple persons in the group hasmoved from a first relatively close position with respect to anassociated vehicle and farther away from the associated vehicle than thefirst position; initiating a timer function in the computer system ifthe information the computer system receives indicates that a first ofsaid multiple persons in the group has moved farther away from theassociated vehicle than the first position; periodically receiving, intothe computer system, updated information, also derived from measured rfsignal strength, indicating whether the first of said multiple personsremains farther away from the associated vehicle than the firstrelatively close position or has moved to a position at least as closeto the associated vehicle as the first relatively close position; andsending a notification from the computer system to at least one deviceassociated with a second person in the group if, after a predefined timeperiod determined with the timer function, it is determined based onreceived updated information that the first of said multiple personsremains farther away from the associated vehicle than the firstrelatively close position, the notification indicating that the first ofsaid multiple persons has remained farther away from the associatedvehicle than the first relatively close position during the entirepredefined time period.
 8. A non-transitory computer readable mediumcontaining program instructions representing software executable in acentral monitoring system comprising a computer system including amicroprocessor memory media and storage media and connected to anetwork, which instructions, when executed by the computer system, causethe computer system to perform method steps for monitoring whetherpersons in a group are each away from an associated vehicle, comprising:receiving into the computer system an association between each ofmultiple persons in the group with one of multiple vehicles;automatically receiving into the computer system digital information,derived from measured rf signal strength via a network, indicatingwhether any one of multiple persons in the group has moved from a firstrelatively close position with respect to an associated vehicle andfarther away from the associated vehicle than the first position; andsending a notification from the computer system to at least one deviceassociated with a person in the group based on received information thata first of said multiple persons is farther away from the associatedvehicle than the first relatively close position is from the associatedvehicle.
 9. The method of claim 8 wherein the step of associating eachof the multiple persons in the group with a vehicle includes receivinginto the computer system an association between a user identificationfor each of the multiple persons in the group and a MAC address of adevice which transmits Bluetooth signals while located in the associatedvehicle.
 10. A non-transitory computer readable medium containingprogram instructions representing software executable in a centralmonitoring system comprising a computer system including amicroprocessor memory media and storage media and connected to anetwork, which instructions, when executed by the computer system, causethe computer system to perform method steps for providing persons in agroup status information and information about the whereabouts of otherpersons in the group, including whether persons in the group have movedaway from an associated vehicle or returned to the vehicle, the methodcomprising: periodically receiving into a computer system informationderived from measured rf signal strength and automatically sent indigital form via a cellular network from one or more portable devices,said information indicating whether any of the persons has moved from afirst relatively close position with respect to an associated vehicle tobeyond the first position and farther away from the associated vehiclethan the first position; periodically receiving into the computersystem, from the portable devices, location information sent via thenetwork for multiple ones of the persons [based on vehicle position]periodically sending updated status information, from the computersystem to each of the portable devices via the cellular network, forgraphically indicating the location of each person on a map andindicating on the map whether each person (i) is at a first relativelyclose position with respect to an associated vehicle (ii) is beyond thefirst position and farther away from the associated vehicle than thefirst position.
 11. The non-transitory computer readable medium of claim10 wherein, according to the method steps implemented by the programinstructions, the location information is periodically sent via thenetwork for multiple ones of the persons based on when a person is atthe first relatively close position with respect to the associatedvehicle.
 12. The non-transitory computer readable medium of claim 11wherein, according to the method steps implemented by the programinstructions, the status information is periodically sent to provideupdates of the status information to each of the portable devices tographically update the location of each person on a map and indicate onthe map whether each person is beyond the first position and fartheraway from the associated vehicle than the first position.
 13. Thenon-transitory computer readable medium of claim 10 wherein, accordingto the method steps implemented by the program instructions, thelocation information is periodically sent via the network for multipleones of the persons based on vehicle position or based on when a personis in the first relatively close position with respect to the associatedvehicle
 14. A non-transitory computer readable medium containing programinstructions representing software executable on a computer systemcomprising a microprocessor and a memory medium and a storage medium,which instructions, when executed by the computer system, cause thecomputer system to perform method steps for automatically monitoring ornotifying when one or more persons in a group move away from anassociated vehicle or return toward the vehicle, the method comprisingthe steps of: storing and providing access to modify a database in thecomputer system which identifies a plurality of portable communicationsdevices, each configured to exchange data with the computer system, thedatabase also associating each portable device with a person in thegroup assigned to have the device in his or her possession; receivinginto the data base position information, derived from a rf signalstrength whenever sent from each portable communications device via thenetwork, indicating whether the person, having possession of theportable device, has moved a distance away from the associated vehicle,the information including data indicating whether each person havingpossession of one of the portable communications devices is (i) in afirst position relatively close to or within the associated vehicle or(ii) has moved away from the associated vehicle to a second position or(iii) has moved from the second position to the first relatively closeposition; and automatically sending, from the computer system to atleast one device connected to receive data via the network, updatedstatus information identifying each person in possession of a portablecommunications device who (i) has moved away from a first positionrelatively close to or within the associated vehicle to a secondposition; or (ii) has moved from the second position to the relativelyclose first position.